Dredging operations are routinely carried out in many water ways where access to a port site is desired. The dredging allows for removal of sedimentation from within a body of water such that the depth of the water column is sufficient for ingress and egress of vessels. However, dredging operations can cause significant harm to the aquatic environment, particularly where sediment is known to be contaminated with heavy metals such as mercury or organic contaminants such as polychlorinated biphenyls.
Resuspension of sediment, whether contaminated or not, into the water column and surrounding environment is always a concern for dredging operations. Resuspension can occur during two phases of the dredging operation, either from the removal activity or from the runoff of water from the stockpiling barge. To minimize the effect of resuspension during the removal activity, the dredging site can be surrounded by aquatic barriers of the type disclosed in U.S. Pat. No. 5,102,261 to Gunderson III or U.S. Pat. No. 6,485,229 to Gunderson III, et al. However, this typically is insufficient for the stockpiling barges, which must be moved to and from the dredging site and, therefore, cannot easily be contained by such barriers.
Stockpiling barges must release excess water during dredging. This is achieved via drainage holes spaced about the perimeter of the barge, typically at the four corners and possibly along the sides. Traditionally, dredgers allow the water runoff to pass through the drainage holes and then spill over the side of the barge. Not only does this add to water turbidity, but it also allows the possibility of contaminated sediments re-entering the water column.
The present invention is directed to overcoming these deficiencies in the art.